# Class 11 - Maths - Trigonometric Functions - Angle on Circular System + NCERT 3.1 Answers. (Part-1)

The phrase "measuring the sides of a triangle" is how the word "**trigonometry**" is obtained from the Greek words "trigon" and "metron." The field was initially created to address triangle-related geometric issues. The surveyors who mapped out the new territories, the engineers, and other people studied it for navigation. Currently, numerous fields, including the science of seismology, the design of electrical circuits, the description of the condition of an atom, forecasting ocean tide heights, analysing musical tones, and many other things.

**You should remember **

1. In the sexagesimal system, we measure angles in degrees, minutes and seconds.

1 right angle = 90°

1° = 60′ (minute) and

1′ = 60′′ (second)

2. In the circular measure, we measure angles in radians.

Thus,

π^{c} = 180°